1. Learn a foreign language

A recent study found that you can boost your knowledge of basic vocabulary in another language while you sleep.

The scientists asked native German speakers to start learning Dutch, and then investigated whether they could influence their retainment of basic vocab while they slept.

The Germans were split into two groups — one was exposed to no sounds while they snoozed, and the other group unknowingly listened to the sound of some of the basic vocab words while they slept. The scientists later tested them on the words, and the group who had listened to them in their sleep could better identify and translate them.

The researchers made sure that these findings were linked to sleep by having another group listen to the words while they did another waking activity, like walking around. They found that the walkers didn’t recall the words nearly as well as the sleepers.

2. Remembering where you put something

This is something many of us struggle with — those frustrating moments of scurrying around the house trying to find your car keys or your cell phone so you won’t be late to work.

Researchers have found that certain memory reinforcing sounds played while you sleep can help you locate where you put an object when you were awake.

In a 2013 study, 60 adults used a computer to place a virtual object in a particular location on the screen. The scientists played a specific tune while they picked the spot to place the object.

This activity was followed by two experiments in which the participants napped for an hour and a half — during the first nap, no sounds were played, and during the second, the scientists played the tune the participants heard while they were placing the object.

None of the participants reported hearing the tune, and unsurprisingly, after either nap, the participant’s memories faded. However, their memories faded less when they had been subconsciously exposed to the memory-activating sound.

Interestingly, the scientists report that their memories were sharper when they were told that the virtual object was of “high value.”

3. Learn musical skills

Learning a new song or instrument can be frustrating, but reinforcing the music while you get some shut-eye can work wonders.

In a 2012 study, researchers taught a group of study participants how to play guitar using a technique from the popular video game Guitar Hero. Then, the volunteers took a nap and were asked to play the tune again once they woke up.

However, the sleeping participants had no idea that half of them would be played the same melody they’d just learned during their nap, while the other half would hear nothing. The researchers report that the participants who heard the sound while they were sleeping played the melody far better than those who didn’t.

If you’re frustrated with trying to learn a new piano piece or guitar tune, put it on repeat while you take a snooze — you could wake up as if you’d rehearsed for hours.

4. Train your brain to retain special memories

With all of the new memories we create each day, there’s unfortunately only so many that our brains can hold onto long-term. Scientists think our brains have a special tagging system to distinguish the critical memories from the less-important ones in order to decide which memories to preserve long-term.

Interestingly, researchers think that there’s a way to hack this tagging system in order to select which memories we want our brains to hold onto.

A 2013 study at Northwestern University showed that people can better preserve the memories of their choice by linking these particular memories — even unimportant ones — to certain sounds.

A group of volunteers had to place icons in specific locations on a computer screen, and each icon was accompanied by a specific noise. For instance, a cat icon had a meowing sound and a bell icon played a ringing sound.

The scientists played these sounds for half of the participants while they took a later nap, and the other group heard nothing. The researchers reported that the people who listened to any of the sounds were better able to recall all of the objects — just one sound helped trigger the memories.

As you have probably noticed by now, there’s a trend in each of these sleep-learning processes: sound. Whether you want to improve your Italian speaking skills or perfect the song you’ve been practicing, it’s a good idea to let your brain soak up the sounds while you sleep.